A suitable self-healing tire puncture sealant must withstand wintertime temperatures to which tires are subjected when standing idle. Such a sealant must also withstand the high temperatures to which tires are heated under summertime driving conditions. These temperatures typically range from -20.degree. F to 270.degree. F. A suitable tire sealant must be capable of sealing punctures when the puncturing object is retained in the tread and also when the puncturing object is removed. Thus, a tire sealant must be capable of adhering to the puncturing object as it works against a flexing tire during travel and must be capable of adhering to itself to seal the puncture after removal of the puncturing object. In addition, the sealant must remain effective for an extended period of time. These conditions require a combination of flexibility, tackiness and strength that are among the most demanding required of any sealant composition. Finally, a suitable tire sealant must be susceptible to economical formulation and application.
Because butyl rubber exhibits low air permeability and high resistance to aging, the prior art has attempted to utilize butyl rubber as a basic compound of sealants. Exemplary of such prior art are U.S. Pat. Nos. 2,756,801; 2,765,018, and 2,782,829. The sealant compositions described in such prior art, however, are inadequate at the temperature extremes to which automatic tires are subjected considering the requirements that such sealant compositions must be resistant to creep and must be self healing.